Constrained networks include, for example, Low power and Lossy Networks (LLNs), such as sensor networks. These constrained networks have a myriad of applications, such as Smart Grid, Smart Cities, home and building automation, etc. Various challenges are presented with LLNs, such as lossy links, low bandwidth, battery operation, low memory and/or processing capability, etc. Large-scale internet protocol (IP) smart object networks pose a number of technical challenges. For instance, the degree of density of such networks (such as Smart Grid networks with a large number of sensors and actuators, smart cities, or advanced metering infrastructure (AMI) networks) may be extremely high. For example, it is not rare for each node to see several hundreds of neighbors. This architecture is particularly problematic for LLNs, where constrained links can wreak havoc on data transmission.
Network deployments utilize a number of different link technologies, including RF, Power line Communications (PLC), and cellular. Each link technology provides its own set of strengths and weaknesses. Devices in these networks typically communicate only via one of these technologies and are commonly referred to as “singly-PHY” devices. An alternative approach is to use network devices that support multiple link technologies simultaneously. Devices in these networks are commonly referred to as “multi-PHY” or “multiple interface” devices. For example, the network devices may support RF and PLC communication interfaces. In certain example devices, devices in these networks utilize a single link technology but differ in the transmission power used by each device. For example, some devices may transmit primarily using low-power transmission channels, other devices may communicate primarily using medium-power transmission channels, and yet other devices may transmit using a combination of medium-power and low-power transmission channels.
Networks are often constrained by regulatory compliance. For example, certain transmission powers (such as “medium” or “low” transmission powers) may be designated for specified channels within each network, and the devices or nodes within the network typically communicate using a channel-hopping link layer. The recipient device determines the channel-hopping schedule, and the sender device must then synchronize with the recipient device and transmit according to the recipient device's channel-hopping schedule.